

class A:
    def test(self):
        print('A test')
    def demo(self):
        print('A demo')

class B:
    def demo(self):
        print('B demo')
    def test(self):
        print('B test')

class C(A,B):
    def demo(self):
        print('C demo')


c = C()
c.test()
c.demo()
print(C.__mro__)  #看搜索顺序